Rb26 Refusing To Run. Please Help. I'm At My Wits End!

[PitlanePhotos]

Ok, it's a long read and I am trying to include as much detail as possible. Please read and help!
So I have been racking my brain for way longer than I would care to admit to, I've read probably hundreds of threads from all over the internet and still have no idea what is wrong with my car.

Background info.
R32 GTR engine swapped for R33 RB26 which had been built by Mercury Motorsport a few years ago and saw seldom use since then.
Engine was running when it was removed from the previous owners vehicle. Sump and cradle were removed to sight internals. Bearings replaced with Cosworth items.
Engine was installed into my car after receiving a few additional parts (see below)
First start up was relatively smooth, built up oil pressure, cranked, started, coughed a bit, knock sensors were not in, this was on a Nistune ECU.

Car info before swap
R32 GTR
R32 RB26
GT2860R -7's
Standard AFM's
Siemens 610cc injectors
Walbro 460LPH pump
Turbosmart E-Boost street

Nistune ECU tuned by MRC Dyno

New Parts
R33 RB26 built by mercury motorsport (forged internals)
Tomei 260deg 9.15mm lift cams
Tomei valve springs
Tomei cam gears (set to 0/0)
Ross Harmonic Balancer

After the initial start up (which I believe this issue was still present, just masked by holding revs around 3k) the car was left for several months.
Nothing significant changed. Battery was replaced, new fuel added, oil and fuel filters changed.

The Issue

The engine will crank, but either struggle to start or cough and die.
Holding a constant throttle the engine will start, sit at approx 1,200rpm, cough a lot and then do one of two things.
Either A. Start firing sporadically incl. firing so early you can hear it firing back into the plenum!
or B. Randomly kick up it's revs, anywhere between 2,000 - 4,000rpm with no extra throttle input at all.
Both of these scenarios usually result in me turning the car off which then results in a loud pressure release sound (nothing venting externally) and me crying quietly in a corner.

Things I have tried
Unplug AFM's = No Change.
Resoldered AFM's = No change.
Unplug 02 Sensors = No change.
Replace Crank Angle Sensor = No change.
Replace igniter module = No change.
Rearrange coil packs = No change.
Replace coil pack loom = No change.

Replace spark plugs = No change.
Replace Nistune with Power FC = No change.

Please. Help?

Edited May 23, 2016 by PitlanePhotos

[Dose Pipe Sutututu]

Are either of the ECUs tuned for the 610cc injectors? Also how is your base fuel pressure and or fuel dampening (if any)?

Btw, Nistune needs the knock sensor flags disabled if you're going to unplug them as you've done

[PitlanePhotos]

Are either of the ECUs tuned for the 610cc injectors? Also how is your base fuel pressure and or fuel dampening (if any)?

Btw, Nistune needs the knock sensor flags disabled if you're going to unplug them as you've done

The Nistune was tuned with the 610cc's. Ran for 2 years with them. The power FC has had the injector %'s and latencies changed to suit.

Fuel pressure is approx 3bar, in tank regulator has been removed, fuel rail reg remains.

The car was run with the nistune, with knock sensors both connected AND disconnected.

And swapping to the Power FC made no difference so I don't see the issue being with the nistune (although it would have been nice and simple)

Power FC does not read any knocking when idle, but does register a tiny amount when the engine is coughing and spluttering as you would imagine.

[Dose Pipe Sutututu]

Are your fuel lines all hard braided Teflon hoses?

Also do you have a wideband connected?

[PitlanePhotos]

Are your fuel lines all hard braided Teflon hoses?

Also do you have a wideband connected?

Not braided. But fresh E85 rated hose.

Fuel is BP ultimate though.

I do not have a wideband connected unfortunately.

[Dose Pipe Sutututu]

Are you able to get it at least running long enough to put a timing gun on it?